ABSTRACT
The conditions at the exterior surface of building components with high insulation are almost independent of the indoor climate. With today’s increasing insulation thickness, the tiny heat flow from the interior is therefore generally not sufficient to prevent a temperature drop below ambient conditions by longwave emission especially during night-time. Apart from the energetic consequences, beneath wetting by driving rain, this temperature drop may lead to surface condensation and subsequently to growth of mould or algae. The results of field examinations of two construction types (ETICS and high insulating monolithic constructions) as well as hygrothermal calculations with a new model, which includes long wave radiation effects, show that ETICS are much more concerned. The reason is their lack of thermal capacity, which means that the energy of the daily solar irradiation is lost short after dawn. A new promising way to decrease the condensation is the application of Infrared-active paints. The positive effect of such a method is demonstrated by hygrothermal calculations and numerous measurements in field tests.
